Medical instruments are frequently coated with various polymers to reduce sliding friction (e.g. by lubricity) and provide other performance enhancing characteristics. Obtaining adequate adherence of the polymer coating to the instrument substrate is a problem in many instances and particularly when a hydrogel is coated on a metal substrate.
Various hydrophylic and hydrophobic polymer coatings and their methods of application have been described in U.S. Pat. No. 4,263,372 Method of coating and/or impregnating porous substrates, and products obtained thereby (Emmons et al.); U.S. Pat. No. 4,435,476 Method of making an abrasion resistant coating on a solid substrate and articles produced thereby (Phillips et al.); U.S. Pat. No. 4,504,528 Process for coating aqueous fluoropolymer coating on porous substrate (Zuckeret al.); U.S. Pat. No. 4,541,980 Methods of producing plastic-coated metallic members (Kiersarsky et al.); U.S. Pat. No. 4,705,584 Application of polymeric materials to substrates (Lauchenauer); U.S. Pat. No. 4,729,914 Hydrophilic coating and substrate coated therewith (Kliment et al.); U.S. Pat. No. 4,784,159 Process for making an implantable device having a plasma sprayed metallic porous surface (Szilagyi); U.S. Pat. No. 5,095,915 Guidewire with flexible distal tip (Engelson); U.S. Pat. No. 5,129,890 Hydrophilically coated flexible wire guide (Bates et al.); U.S. Pat. No. 5,235,964 Flexible probe apparatus (Abenaim); U.S. Pat. No. 5,290,585 Lubricious hydrogel coatings (Elton); U.S. Pat. No. 3,969,552 Process for impregnating porous articles (Malofsky et al.); U.S. Pat. No. 4,147,821 Impregnation of porous articles (Young); U.S. Pat. No. 4,556,701 Impregnate compositions for porous substrates (Schindler et al.); U.S. Pat. No. 5,333,620 High performance plastic coated medical guidewire (Moutafis et al.); U.S. Pat. No. 5,441,488 Medical tool having lubricious surface in a wetted state and method for production thereof (Shimura et al.); U.S. Pat. No. 5,443,455 Guidewire and method of pretreating metal surfaces for subsequent polymer coating (Hergenrother et al.); U.S. Pat. No. 5,443,907 Coating for medical insertion guides (Slaikeu et al.); U.S. Pat. No. 5,437,288 Flexible catheter guidewire (Schwartz et al.); U.S. Pat. No. 5,573,520 Flexible tubular device for use in medical applications (Schwartz et al.); U.S. Pat. No. 5,749,968 Device for priming for improved adherence of gels to substrates (Melanson et al.); U.S. Pat. No. 5,750,206 Method of pretreating metal surfaces for subsequent polymer coating (Hergenrother et al.); U.S. Pat. No. 5,833,632 Hollow guide wire apparatus catheters (Jacobsen et al.); U.S. Pat. No. 5,700,559 Durable Hydrophilic Surface Coatings (Sheu et al.); U.S. Pat. No. 6,080,488 Process for preparation of slippery, tenaciously adhering, hydrophilic polyurethane hydrogel coating . . . medical devices (Hostettler et al.); U.S. Pat. No. 6,149,978 Coating of porous, hydrophobic substrates with thermoplastic fluoropolymers (Bladel et al.); U.S. Pat. No. 6,162,310 Method for producing porous sponge like metal (Tseng); U.S. Pat. No. 6,176,849 Hydrophilic lubricity coating for medical devices comprising a hydrophobic top coat (Yang et al.); U.S. Pat. No. 5,840,046 Guidewire Having Hydrophilic Coating (Deem); U.S. Pat. No. 5,984,878 (Multi-Coating Stainless Steel Guidewire (Engelson) as well as PCT International Patent Publications WO 92/11877 Biocompatible abrasion resistant coated substrates (Fan et al.) and WO 00/65143 Process for coating a perforated substrate (Munro et al.), all of which are expressly incorporated herein by reference.
One reason for applying polymer coatings to insertable medical devices is to impart lubricity to, or to lower the coefficient of friction of, the outer surface of the device. Some of these polymer coatings, such as fluorocarbon coatings (e.g., polytetrafluoroethylene) provide a lubricious hydrophobic surface while others such as swellable hydrogels are hydrophilic and become lubricious after coming in contact with liquid (e.g., blood or other body fluid).
For example, U.S. Pat. No. 5,573,520 (Schwartz et al.) describes a flexible tubular member encased by a fluid tight polymer covering, including a hydrogel, for use as a guidewire, catheter or introducer. However, the polymer covering is only described as covering either the inside surface or the outside surface for the purposes of a fluid tight sealing of apertures or for providing lubricity. As described earlier, these benefits of coatings are known in the art. However, Schwartz et al. does not describe the coating to be integral to the wall of the device or there being any sort of interlock or other improved attachment of the coating.
Also, U.S. Pat. No. 5,840,046 (Deem) describes guidewires having hydrophilic coatings, such as hydrophilic polysaccharides (e.g., hyaluronic acid or chondroitin sulfate). The guidewires are made of wire which is helically coiled about a core member. The spacing between adjacent coils of the wire is wide enough to allow the coating to flex along with the coil but narrow enough to prevent the coating from penetrating into an annular space that exists between the coiled wire and the inner core member.